In the good old days, Texans went to "Mexican restaurants" and ate "Mexican food." Then in 1972, The Cuisines of Mexico, an influential cookbook by food authority Diana Kennedy, drew the line between authentic interior Mexican food and the "mixed plates" we ate at "so-called Mexican restaurants" in the United States. Kennedy and her friends in the food community began referring to Americanized Mexican food as Tex-Mex, a term previously used to describe anything that was half Texan and half Mexican. Texas Mexican restaurant owners considered it an insult.

But by a strange twist of fate, the insult launched a success. For the rest of the world, "Tex-Mex" had an exciting ring. It evoked images of cantinas, cowboys and the Wild West. Dozens of Tex-Mex restaurants sprang up in Paris, and the trend spread across Europe and on to Bangkok, Buenos Aires and Abu Dhabi. Tortilla chips, margaritas and chili con carne are now well known around the world. In this series of articles, we reconsider Tex-Mex in light of its international reputation as America's most popular regional cuisine.

In the first article in this series ("Pralines and Pushcarts," by Robb Walsh, July 27), we met the pioneers of Tex-Mex: the pecan candy and tamale vendors who sold their wares in the streets of Houston and other Texas cities from the 1880s until the turn of the century.

The cloud of steam and the deep pool of thick brown sauce make it impossible to tell where the enchilada starts and the refried beans end. There is a tamale under there, too, somewhere. The No. 1 dinner at Felix Mexican Restaurant [904 Westheimer, (713)529-3949] ($7.25) starts with a beef taco and a tostada on one plate and continues with a second hot plate covered with the brown sauce, called chili gravy on Felix's menu. It resembles the flour-based brown gravy you might find on a Salisbury steak or a roast beef plate at the Piccadilly Cafeteria, but with comino and chili powder added.

I believe that the taste of chili gravy explains Tex-Mex more eloquently than words ever will. The thick brown gravy with Mexican spices is neither Mexican nor American. It wasn't created in the homes of Texas Mexicans, either. It was invented in old-fashioned Mexican restaurants that catered to Anglo tastes. But what's amazing about it today is the way it illustrates how our tastes have changed.

Felix's Mexican food tastes absurdly old-fashioned because it's geared to the Anglo palates of the 1950s, and it has never changed. How do I know? Because Geneva Harper told me. Harper was there when Felix's flagship location on Westheimer near Montrose opened in 1948. And she was there when I stopped by for lunch last week. "The cheese enchiladas with chili gravy on the Mexican Dinner haven't changed at all since the place opened," she said. "Except that a Mexican Dinner went for 50 cents in 1948."

The 91-year-old Harper worked for owner Felix Tijerina for more than 50 years. "He was a wonderful man," she said. Indeed he was. In fact, Tijerina, whose accomplishments went far beyond his restaurants, was one of the most inspiring figures in recent Texas history. But he also wrote an important chapter in the history of Tex-Mex food.

Tijerina's story is a study in assimilation. His mission was to help Mexican-Americans merge into the American mainstream as successfully as he had. His cooking style was not about bringing authentic Mexican flavors to Texas; it was about putting Anglos at ease with things Mexican. His floury chili gravy and fluffy chili con queso were not far from brown gravy and cheese dip, and the spicing of his sauces was nonconfrontational to the delicate Anglo palate. Early Mexican restaurants like Felix's were among the first institutions where urban Anglos and Hispanics rubbed elbows. Tijerina's Americanized version of Mexican cooking was what brought the races together. And it was a triumph of diplomacy.

At the turn of the century, tamale vendors, chili stands and other such street sellers supplied the Mexican food in Houston. But in 1907 a public crusade for better sanitation began to force them out of business. The civic reforms of the Progressive era brought about the first health inspections and rules for safe food handling. William McDuffie Brumby, Houston's crusading health officer, led these reforms and then went on to become president of the Texas Board of Health, where he wrote a statewide sanitation code. While some tamale vendors and chili stands remained in business after 1910, their numbers dwindled as permanent Mexican restaurants with more hygienic facilities began to take their place.

The first Mexican restaurant listed in Houston's city directory was the Original Mexican Restaurant at 807 Fannin. It was opened in 1907 by George Caldwell, an Anglo from San Antonio. Caldwell was no doubt inspired by the Original Mexican Restaurant in his hometown, which opened in 1900. Caldwell's place was quite popular and a favorite of mayor Oscar Holcombe's. Caldwell's slogan was "Genuine Mexican food, properly prepared."

In 1918, 13-year-old Felix Tijerina took a job as a busboy at the Original Mexican Restaurant. Tijerina was born in Sugar Land to migrant cotton pickers. While he worked at the restaurant, he taught himself English and became a friend and trusted associate of Caldwell's, rising to the rank of manager. In 1922 the Original Mexican Restaurant moved from its first address on Fannin to a larger location at 1109 Main.

With Caldwell's encouragement, Tijerina opened his own Mexican restaurant in 1929. He had learned Caldwell's formula well: Promise authenticity, but deliver the kind of Anglo-friendly food that Houstonians actually eat.

The Depression put Tijerina's first restaurant out of business, but in 1937 he built another one on Westheimer in River Oaks. Felix and his wife, Janie, slept in the back of the restaurant and worked virtually around the clock turning the operation into a huge success. He opened an outlet in Beaumont, another in Bellaire and the flagship restaurant on Westheimer near Montrose. He would go on to build six altogether, creating one of the most successful restaurant empires of his day. "For the finest in Mexican foods" was Tijerina's slogan.

But fine Mexican food isn't really what Felix Tijerina is remembered for. A veteran of Mexican-American voter registration drives going back to the 1930s, Tijerina was among the city's earliest Hispanic activists. As a successful businessman, he became friends with Roy Hofheinz, R.E. "Bob" Smith and Louis Cutrer, and was the first Mexican-American appointed to serve as a board member of the Houston Housing Authority. Tijerina also rose through the local, regional and state levels of the League of United Latin American Citizens. In 1956 he was elected the organization's national president and served four consecutive annual terms. As president of LULAC, Tijerina started the Little Schools of 400.

At the time, Mexican-American students suffered an extremely high dropout rate. Tijerina believed that if Spanish-speaking students could learn a little English before entering elementary school, they might stand a better chance. A pilot program was started in 1957 in Ganado, southwest of Houston and just north of Port Lavaca. Tijerina paid a 17-year-old named Isabel Verver $25 a week to teach five-year-old Hispanic children 400 words of English. All the children in the program successfully completed first grade in a school system that had a poor track record with Spanish-speaking kids: It had failed 50 percent of them the year before.

Governor Price Daniel asked Tijerina to expand the Little Schools of 400 program to other Texas cities. Speaking on Spanish-language radio stations across the state, he urged Mexican-American parents to get their children involved.

Felix Tijerina went from a 13-year-old busboy who didn't speak a word of English to the most prominent Mexican-American in Houston and one of the state's Hispanic leaders. Politicians such as Ralph Yarborough courted his support. He was even invited to the LBJ ranch to consult with Lyndon Johnson about educational programs. His efforts to educate Spanish-speaking kids made quite an impression on the future president.

Felix Tijerina's Little Schools of 400 became the inspiration for LBJ's Head Start program.

In the spring of 2001, Texas A&M University Press will publish a biography of Tijerina, Mexican American Odyssey: Felix Tijerina, Entrepreneur and Civic Leader, 1905-1965, written by Thomas H. Kreneck. The author worked on the book in conjunction with the University of Houston's Center for Mexican-American Studies.

"Felix Tijerina was the most prominent Mexican-American in Houston," Kreneck told me. "And as a four-term president of [LULAC], he was also nationally famous. Leaders like Tijerina are part of what scholars call the Mexican-American generation, the era of political activists who moved Mexican-Americans from the facelessness of the 1910s to the limelight of public attention in the 1960s. These leaders articulated Mexican-American concerns to the society at large and put their issues on the national agenda."

The Daily Special ($5.95) never changes at Felix Mexican Restaurant: It is two chicken enchiladas in Spanish sauce with shredded iceberg and chopped tomatoes on the side. The "salad" has no dressing, but there is a big scoop of sour cream with it. As you eat the enchiladas, the cold lettuce and tomatoes get mixed in with the hot tomato sauce and chicken juice. In fact, the Daily Special might be accurately described as a chicken enchilada salad. There is hardly any chili pepper bite to the sauce, which appears to be a simple combination of well-cooked tomatoes and onions.

"It tastes so old-fashioned," said a friend who came along to lunch recently. "It reminds me of my childhood. The chicken and the soft tortillas with sour cream, it's like chicken and dumplings, comfort food."

Between the 1970s and 1980s, the "American melting pot" was being replaced by the "American mosaic" as the official metaphor for ethnic assimilation. At the same time, America's tastes in food were growing more adventurous. Influenced by Diana Kennedy and other proponents of authentic Mexican cuisine, food lovers sought more assertive flavors. Old-fashioned Mexican food like Felix's began to be referred to, condescendingly, as Tex-Mex.

A crop of restaurants that reflected the new mood, including the original Ninfa's on Navigation, sprang up starting around 1973. Their slogans promised authenticity, just as the Original Mexican Restaurant and Felix had before them. "Our food is so Mexican, don't drink the water here," read the sign for a defunct Mexican restaurant across from Market Square Park. But in fact, the new Mexican restaurants weren't much more authentic than the ones they replaced. The new menus touted fajitas, soft (flour tortilla) tacos, chimichangas, burritos and other dishes of Mexican-American ancestry that were unknown in Mexico City. This new kind of Mexican food featured fresh spicy salsas, charcoal-grilled meats and seafood, and dishes that seemed much more distinctive than the combination plate. Monterrey House, El Chico and the other giants of 1950s-style Tex-Mex declined in popularity or went out of business. A few old Tex-Mex restaurants, like Molina's [5227 Buffalo Speedway, (713)432-1626; 7901 Westheimer, (713)782-0861; 3601 South Highway 6, (281)497-1800], Loma Linda on Telephone Road, the Original Mexican Cafe in Galveston [1401 Market, Galveston, (409)762-6001] and Felix's last restaurant on Westheimer, seem to remain open for reasons of nostalgia. Run by Felix Tijerina Jr., the lone Felix location is frequented mainly by patrons who have been eating there for half a century.

Here are a few of the entries in the guest book that stands in Felix's foyer:

"My husband and I ate here regularly in the '50s. This is a nostalgia trip for me. The food is as delicious as I remember it."

"I have been coming here my whole life. This is my favorite restaurant. I came from New Braunfels four hours away."

"We have been coming here since the early '50s; we remember Mr. Felix."

If Felix's customers all appear to be over 60, across town at Molina's on Buffalo Speedway, most of the tables seem to be occupied by people under 12. I order the Mexico City Dinner ($8.55) because of the irony of the name. The first plate includes a beef taco, a bean tostada, a puffy taco with queso and an order of guacamole. The second plate is made up of cheese enchiladas in chili gravy, a tamale with chili con carne, and rice and beans. Pecan pralines are included in the price of the dinner, just like in the good old days. I can just imagine what the Mexican food snobs would have to say about puffy tacos and chili con carne.

Molina's combination plate is similar to Felix's, but the chili gravy has more bite and better body. It's made with ancho peppers and a lard-and-flour roux. Molina's was founded in 1941 by Raul Molina Sr., who is now in his nineties. His son, Raul Molina Jr., is semiretired as well. The operation is now run by the third generation of Molina family restaurateurs, including Raul the third.

The amazing thing about Molina's is all the kids eating here. Outside in the parking lot, I approach a family leaving the restaurant. Ken and Martha Johnson tell me they are from Bellaire as they secure their daughters, Caroline, eight, and Annabelle, six, in the backseat of a Honda minivan. I ask them why they chose Molina's for dinner.

"The kids like it. They eat their dinners," Martha Johnson tells me.

I ask her if she doesn't prefer other Mexican restaurants with spicier food and more modern dishes. "Yeah, but if we go somewhere where the food is spicy, the kids won't eat. And then when we get home, they say they're hungry and we have to feed them again," she says. She admits there's a nostalgia factor, too. "I grew up eating this kind of classic Tex-Mex. But the truth is, we don't like our food as hot as we used to, either."

From the "genuine Mexican food" of George Caldwell in 1907 to the claims you hear today, Mexican restaurants have always promised authenticity and have always delivered what sells. The real changes that have taken place are in the public's tastes. And understanding the way our tastes have changed can tell us a lot about where we're going and where we've been.

Texas is a bellwether for those who see American society entering an era of Hispanicization. According to some thinkers, as the Hispanic population increases, so does its influence on the American culture at large. To experience the evolution of Tex-Mex, from its bland beginnings in the Felix Tijerina generation to the hot and spicy version we eat today, is to experience American culture changing before your very taste buds.

When I take people to Felix or Molina's or the Original Mexican Cafe in Galveston and tell them this is an incredible opportunity to see what Tex-Mex tasted like 50 years ago, they look at me like I'm crazy. "So where do you go to get authentic Mexican food," a tablemate at Felix asked me after he tasted the beef tamales with bland chili and beans ($5.95).

It's hard for people to understand why they should want to eat old-fashioned Tex-Mex. Let me put it this way: You eat at these old Tex-Mex places for the same reason that you listen to scratchy old recordings of the Delta blues. It's not about the quality; it's about getting in touch with the roots of American culture.